Piston device



Patented Sept. 17, 1946 UNITED STATES PATENT OFFICE` PISTON DEVICE Sidney G. Down, Edgewood, Pa., assignor to The Westinghouse Air Brake Company,

Wilmerding,

Pa., a corporation of Pennsylvania Application October 22, 1942, Serial No. 462,907

6 Claims.

of lubricating means suitable for use in lubrieating the pistons and cylinder walls of brake controlling devices for iiuid pressure brakes.

It is especially desirable with Vcontrolling devices for uid pressure brakes to maintain` a consistent minimum of friction between the piston and packing ring and the bushing in Which they are reciprocable in response to variations in the pressure of fluid on opposite sides of the piston. Limited andperiodic lubrication has been found to be one of the best methods for maintaining this minimum of friction over an extended period of time and the provision of novel means whereby this is accomplished is one of the objects of this invention. l

One method for providing automatic lubrication over an extended period of time is by feeding lubricant through capillary attraction means to the cylinder Walls and the periphery of the piston at a slow continuous rate. This method has a disadvantage in that it is difficult to meter the supply of lubricant at a Slow enough rate to provide the desired lubrication. Also, the flow continues at substantially the same rate regardless of the extent of active service the valve device has experienced. Thus, a rate of ilow of lubricant that is barely suflicient for a valve device in highly active service would be excessive and harmful in another in inactive service. An excess of lubricant has a tendency to collect dirt or get gummy thereby increasing the friction between the piston and cylinder bushing to an abnormal degree. y

In other methods a breather port to` convey the lubricant from a wick, capillary tube or the like to the piston ring groove is employed. This port acts, upon a reduction in pressure of the fluid in the brake pipe in a train brake system, to direct the resulting flow of uid from a` lubricant reservoir in the piston to the ring groove across or through a lubricant collecting and dispensing element and in the direction of the ring groove. These methods though they maintain a relation between the rateV of feed of lubricant and the activity of the valve device, too frequently provide an undesirable excess of lubricant to the friction surfaces. Y c c It is the object of my invention, to correlate the rate of feed of lubricant` with a periodic function which occurs at less frequent intervals by nullifying the` breather action and therebythe lubrication of the partsV during serviceqapplications of the valve device and rendering it leiiective onlyduring emergency applications. In this manner it will be 'possible to supply a smaller amount of lubricant to the friction surfaces. Periodic operation is assured since the emergency application of the valve device is rarely used during the interva1 of a train trip and is consistently used when the car is set on a railroad siding.

To effect the above objects an inertia or fluid pressure controlled element may be used in combination with breather type lubrication means to render the lubrication means operative only during an emergency application of the train brakes. The piston of the brake controlling valve device is provided with an additional or breather passage which is preferably arranged parallel to the lubricant conducting passage between the lubricant reservoir and the ring groove and which by-passes the lubricant conducting passage and renders it substantially ineffective during service applications. c l

The piston is further provided with an inertia element in the form of a cylindrical valve adapted to close on the breather passage when the piston is moved rap-idly and stopped abruptly as during an emergency application of the brakes. The continued reduction of the pressure of fluid outside the ring groove causes the uid in the lubricant reservoir to now to the ring groove through the lubricant conducting passage carrying With it the lubricant that has collected in the port by capillary attraction.

In the accompanying drawing Fig. 1 is a fragmentary sectional view of an emergency portion of the type employed in the AB type of railway car `brake equipment; showing the invention embodied therein; Fig. 2 is a fragmentary sectional view showing a modication of the invention; and Fig. 3 is a sectional view similar to Fig. 2 but showing another modification of the invention.

As shown in Fig. l, the emergency portion of the equipment may comprise a brake controlling valve device having a bushing I which is of the usual tubular form and may be made of any suitable material, such as brass or molded plastic composition. This bushing is adapted to be pressed into a suitable bore 2 inthe casing 3. 'I'he bushing is provided with a charging port 4 which connects with a passage 5 leading to a valve chamber 6 and with the usual quick action chamber not shown. l

Slidably mounted in the bushing for reciprocatory motion relative thereto is a piston l having a groove 8 formed in the periphery thereof, in which groove is mounted the usual packing ring 9 which may be of'any suitable material such as brass, and which, due to its inherent resiliency, is pressed outwardly into close frictional engagement with the inner friction surface of the bushing l.

The piston is'provided with a stem l0 which is adapted to operate the usual emergency slide Voir I in which a suitable amount of lubricant.

is carried, which lubricant is supplied to the i tight screw-threaded connection with the, piston.,

The piston is further provided with a lubrichamberV through an opening provided inthe 1 cant conducting passage Iii extending radiallyV upward from the reservoir I4 to the bottnm of the ring groove 8. This passage is for the purpose of permitting the Aflow of lubricant to the groove B under certain conditions to be moreV fully de-` scribed. A

Contained inthe reservoir 'it and"v covering the inner end ofthe passage I6 is a lubricant collecting and storage element Il to which lubricant is ,l

supplied by a Wick I8.A The lubricant collecting and storage element ilcomprises a disc of compressible Inaterialsuch as'felt'and is engaged by a...s pring` t9 vwhich serves two purposes; first, to

' maintain the element in its proper relation to the passage I5. and second, to compress the element theamount necessary to ylimit itslubricant collecting and storage, capacity to the requisite amount. The upper fend ,2S of the spring Iii-is turned upwardly sc tl'rat it extends through the storageelementr and intothe passage IE5, thus positioning thejelement IIj with relation to the passage. The lower endof this spring is seated on the bottom of the reservoir le.

` The'` wick I8 is preferablyintegrally attached tothe element I7 and preferably extends from theY element to the bottom of the lubricant reservoir-I4. This wick conducts the'lubricant from the main4 supply .to the -element ,by capillary attraction;` i .i Y

The piston is furtherV provided with an axial bore `2l in which is .carriedy a cylindrical inertia element 22. This bore, 2l joins the posterior of the lubricant reservoir ,I4 and is also in lcommunication Withfthe ring groove.l 8 by means of a' by-pass passage 23.

The by-pass passage ZBveXtends radially upward Ifrom the axial bore 21| tothe groove 8 and Vfor Athe *greatery portionv of yits length is parallel to, the lubricant conducting passage Ij6. This passage 23 joins the K.axial bore ZI at a point a short distance to the left of the iuncture of fthe boreV and the reservoir ttl-,- where it maybe sealed off by the inertia element 22 upon Vits movement outof normal position toward the front of' the piston, thus the element serves as a valve for 4 until the charging port 4 is uncovered to the chamber 2B at the face of the piston. Fluid Will flow. by way ofthe charging port 4 and the passage 5 to the valve chamber Sbehindthe piston.

At the same time fluid will flow at a slow rate ypast the periphery of the piston and through the necessary clearance space between the packing ringland the piston to the open space defined by the inner surface o f the ring and the bottom of the ringpgrooveandfrom thence flows through l the passage 23 and. bore 2I to the lubricant reservoir I4', thus slowly increasing the pressure of fluid in thereservoir to substantially the same pressure as that acting on the face of the piston. From this space, fluid under pressure may also flow by Way of the passage i' to the reservoir iii but due tothe 'resistanceoered by the element i-I Ato such flow the'lmajorY portiono'f' the flow will be; by way of passage'l23.

To effect an emergency application of: 'the brakes in a train of railway cars the pressure of fluid inthe train brake pipe and in piston chamber 28 at the face ofr the piston is rapidly reduced t0 preferably atmospheric pressure. Upon such a'reduction inbrake pipe pressure the fluid pressure in the chamber f'located to the left of the piston, propels the piston forwardly rapidly until it strikes the gasket I31at the right hand end of the chamber 28 thus bringing the `piston to an abrupt stop. The slide valve II,` which is actuatedby the piston, comes to a stop with the piston in a position wherein,` 'in the emergency portion of a fluid pressure brake equipment of the AB type. connections are established by which the fluid under pressure in the chamber 6' is vented to atmosphere at a certain slow rate. e When the piston isA stoppedV abruptly as just described, the linertiaI element 22 continues to move forwardly in itsbcre ZI relative to theenow stationary piston and against the opposing -pressure of the spring landcovers the mouth of the by-pass passage 23. Since the fluidA in the lubricant reservoir I4` is ata higher pressure than that i outside of the piston ring,1f`luid"willow from' the reservoir through the lubricant saturated element jII and the'lubricantV conducting passage I6 tothe ring vgroovegand fromv thence willnow past the packing ring to the periphery ofthe piston and to chamber 6, the flow to brake pipe having been blocked off at this time by the bead I2 of the l piston-making a sealing engagement with the controlling communication between the passage 23v and the bore 2I. I

The inertia lelement 2v2 is normally held against the backend of the bore 2i by means of a light spring 24, which is seated ina central recess 25 provided inthe element. The right hand end 26'4 ofthe vspring 24 is doubled back so that it extends along the axis'of the' springI to itsVV opposite end Where it passes through a hole ZI in the inertia element and .thenA into a recess formed in the .pistonwhereit isanchored in thepiston as shown.

v,Vlhen the.v brake.controlling1 valvedevice is placed inservice, the pressure offiiuid supplied by Way. of the usual brakev pipe, not shown, and acting cnthe. face of the piston 'i will be increased and will move the piston'in the direc.-

ytionthoward,the leftf-handasviewed. in Fig. 1

gasket I3;

The fluid as'lit passes through the lubricant saturated element I'I, picks up a portion of the lubricant and carries or forces it through the passage 'I6 to the piston packing ring groove 8 and against the rear and side surfaces'cf `the packing rmg.

Lubricant thus supplied tothe groove Will flow within the groove'A along thepiston so as to supply lubricant throughout the entire circumference of the piston. Y

The piston' packing ring' 9V fits the ring groove 8 closely, hence lubricant deposited on the ring will ow byY capillary vattraction to the outer friction' surface Vof the'ring and tothe friction surfaceA of bushing I. As therpi'ston is reciprocated during subsequent service operations thev` lubri- V fcant will be spread evenly over `the cooperating sur-facesof the ring anri'bushir'ig.VV Y It Will bel noted;tl'ljatA during v service applicaf tions o f the brake4 thereductionsinthe; pressure of thefluid in the` brake: pipe are notatsuch a'rapid rate, nor rto nsuch'wanuamounias those Gf` emergency. applications; .Threfvre'ihe @were gency piston 'I will not ystrike the gasket I3 and the inertia element 22 Willnot be moved out of its normal position, consequently the by-pass passage 23 will be open. Fluctuations in pressure of the fluid on the face of piston will not create any substantial pressure differential acrossthe lubricant storage `element I'I.`since the pressure of uid in the lubricant reservoir and pressure of uid in the ring groove will be equalized by a less restricted ow through passage IS. l

It has been found in practice that it is not diiicult to conduct an over-supply of lubricant to the parts to be lubricated, the diiculty being in limiting the supply to the small amount which it has been ascertained is suliicient to maintain the frictional resistance offered by the cooperating parts substantially low and constant.

By limiting the lubricant supplying times to emergency operations of the emergency portion of the equipment the amount of lubricant supplied to the cooperating surfaces will not be excessive. i

In Fig. 2 a modification of the inertia element arrangement is illustrated. In this arrangement relative movement between the piston 'I and the inertia element is provided when the piston starts suddenly or is brought to an abrupt stop.

As illustrated, the inertia element is indicated by the reference numeral 29 and is located intermediate the ends of the axial bore 2l by means of light compression springs 36 and 3|. The element is provided in the middle area of the periphery with an annular groove 32 from which a series of passages 33 extend radially inward to communicate with the central spring well 34 of the element 29, which communicates with bore 2I and lubricant reservoir I4. In normal position of the inertia element the groove 32 registers with the by-pass passage 35 in the body of the piston.

When the pressure of fluid in the brake pipe is reduced at a moderate rate, as during a service application of the brakes, the piston will change its position slowly and without sudden starting and stopping. Thus, during service applications, there will be no relative movement between the piston and element and as a result the pressures in the lubricant reservoir I4 and the ring groove 8 will be equalized, so that the lubricant passage I 6 is rendered ineffective. However, when the pressure in the brake pipe is reduced rapidly, as for instance during an emergency application, the piston will start to move suddenly. As a result, the inertia element 29 will move to the left, covering by-pass passage 35A vand interrupting any lnow of fluid therethrough. Lubricant will be carried to the ring groove 8 as previously described. When the piston` is stopped suddenly the function will be the same as that described for Fig. 1. In passing from the extreme left end of axial bore 2| to the extreme right end, groove 32 in theelement 29vwi1l connect brieiiywith passage 35. Because'of the rapid movement, the interval of communication between the groove 32 and the passage 35 will be so short as to be negligible.

In Fig. 3 another modification of my invention is shown wherein a pneumatically controlled valve is provided which is operative only during emergency applications of the brake.

In this form of my invention the iilling plug 3B for the lubricant reservoir I4 is modified to make a sealing engagement with a valve 3'! which is interposed Ibetween the lubricant chamber and a passage which by-passes the lubricant collecting and storage element I1 and permits the equalization of the fluid pressures in the lubricant carrying passage I6 and the lubricant reservoir I4. The valve 3l is preferably of the disc type having a guiding skirt IIIIi and is carried in a cylindrical chamber 38 in the piston body, into which chamber the lling plug 36 also extends. The valve is provided with the necessary number'of ow restrictive openings 4I extending through that portion of the disc which is outside the seating area. An annularseat rib 39 is provided at the inner end of plug 33 for engaging the valve 31 which is held out of engagement by a spring 42 contained in a central recess 44 in the plug. The plug 36 is also provided with passages 43 extending radially outward from the chamber 44 to connect with an annular groove 45 in the piston body, when the plug 36 is screwed tightly into the piston, the groove communicating with 'a bypass passage 46 leading from theY lubricant carrying passage I6. Thus, free communication is normally established between the ring groove 8 and the lubricant reservoir I4 by way of the lubricant carrying passage I6 and also by Way of openings 4I in valve 31 to chambers 36 and 44 which communicate by way of passages 43 in plug 36, groove 45 in the piston body "I, and bypass passage 46 to lubricant carrying passage I6.

During service brake applications, when the pressure of uid in the train brake pipe is reduced at a rate, to effect a service application of the brakes, valve 31 will remain in its normal unseated position, since the openings 4I are of sufcient flow capacity to permit iiuid to flow at the same rate from the chamber 38.` But when fluid pressure in the train brake pipe is reduced rapidly, as during an emergency application of the brakes, uid under pressure will be conducted away from chamber 33 by way of chamber 44, passages 43, groove 45, by-pass passage 46 and lubricant conducting passage I6 to the ring groove 8 more rapidly than it can flow through the restrictive openings 4I in the valve 3l. Consequently pressure of iluid acting on the right hand side of valve 3'! will be reduced to the extent that the pressure of fluid acting on the left hand side of valve 31 will overcome the opposing pressure of the spring 42 and the valve will make a sealing engagement with the seat rib 3S. This will interrupt any further now of fluid through the openings 4I and enough differential in iluid pressure `will be developed across the lubricant storage element I'I to initiate a flow of fluid therethrough carrying lubricant to the ring groove 8. l

From the foregoing description it will be apparent that with each form of the invention disclosed the piston will be lubricated only when an emergency application of the brakes is being effected thereby avoiding the delivery of excessive lubricant to the parts to be lubricated.

Having now described my invention, what I' claim as `new `and desire to Patent, is t 1. In a lubricating apparatus for the cooperating friction surfaces of two members, at least one of which is movable relativeto the other, a fluid pressure chamber to which a surface. of the movable member is exposed and in which the pressure of iuidmay be varied, a lubricant storage reservoir formed insaid movable member and adapted to receive a lubricant, a passage leading from said reservoir to at least one of said surfaces and to said chamber, said passage constituting a communication through which uid under pres- `secure by Letters stricted flow capacity than the first mentionedA communication through which fluid under pressureY may breathe into and out Vof said reservoir in response to variation in the pressure of fluid insaid chamber, and said second passagebeing normally open so as to inhibit the flow of fluid andI thereby the lubricant through the 'ilrst mentioned passage, and inertia means operative upon avsudden change in the speed of said,V movable member for inhibiting the flow of fluid from said reservoir to said second passage, so that fluid flows from the reservoir to the first mentioned passage.

2. In a lubricating apparatus for the cooperatingfriction surfaces of two members, at least one of which is movable relative to the other, a fluid pressure chamber to which a surface of the movablermember is exposed and in which the pressure of fluid may be varied, a lubricant storage reser-Y voir formed in saidmovable member and adapted to receive a lubricant, a passage leading from lsaid reservior to at least one of saidfsurfaces and to= said chamber, said passage constituting a communication through which fluid under pressure may flow from said lubricant reservoir in response to a reduction in the pressure of fluid in said chamber, means adapted to supply lubricant from saidlubricantstorage reservoir to the fluid which flows from the reservoir to said passage, a passage means for by-passing said passage and constituting a communication through which fluid under pressure may breathe into and out of saidlubricant sto-rage reservoir in response to variation in the pressure of uid in said chamber, the. latter communication being normally open and less restrictive than theformer communication so as to divert the flow or fluidv to the bly-pass passage means, an inertia means operative upon a sudden change in the speed of said movable member asv it is moved in response to the sudden reduction in the pressure of fluid in said chamber to render said by-passpassage means ineffective, so that fluid flows from the reservoir to the first men- -tioned passage.

3, Ina piston device, the combination of a cylinder, a piston mounted in said cylinder to form a chamber at each side of said piston, said piston being ,reciprocable in response to variationsin the pressure of fluid in one of said chambers, and a lubricating apparatus comprising a lubricant reservoir formed in said piston and adapted to contain lubricant, a passage leading from said reservoir to the periphery of said piston and to said chamber, means for conducting lubricant in said reservoir to said passage, said passage being adapted to conduct fluid and lubricant supplied thereto to the periphery of said piston upon areduction in the pressure of fluid in said chamber, asecond passage communicating with said reservoir and said chamber adapted to conduct fluid from said. reservoir more freely than the first said passage, and valve means operative upon .a sud- 'den change yin the speed-ofsaidfpiston-inducedfby aisuddenreductionin the pressureof fluid-in said chamber to interrupt vthe flowof fluid under pres'- sure from said reservoir to said second mentioned passage. Y Y Y 4. `1in apparatus for lubricating alf/ricti'on surface of a movablefmember, in combinatiomfaflubricant storage reservoir formed in said movable member and adapted to containlubricantymeans for maintaining saidrese-rvoir normallycharged with fluid under pressure, two passages through whichfluid under pressure containedfin-saidsreservoir may flowmeans conducting lubricantein said reservoir to one of -said passageswhich pas'- sage adapted to carry lubricant from said means to saidl surface by fluideflowingfrom .the

reservoir, the other passage ybeing normal-lyopen so that when fluid flowstherethrough fromsaid reservoir it will inhibit the flow of fluid through said one passage, andy inertia'means responsive to a sudden changein the speed of the movable member for closing communication betweenrsa-id reservoir and said otherA passage whereby fluid under pressure and thereby lubricant 4mayflow through said one passage only;

5. In a lubricating appa-ratusofV the typef'co'm-iprising Aa movable member having' a surface `to belubricated, said member lbeing providedwith a lubricant storage reservoir and. a lubricant con-'- ducting passage having associated therewitha lubricant, carrying member and through which fluid under pressure may'flow Yto thereby carry lubricant from saidv reservoir to said surface; =in combination, means for maintaining said reservoir normally charged withflud under pressure, another passage normally open to 'said reservoir and to said lubricant conducting lpassageV for equalizing the pressure of fluid thereinso that 1no effective amount `of fluid flows through thelubricant conducting passage, and means operative upon a sudden change. inthestate of'moticn of said member for-closing said otherfpassage:

6. In a fluid pressure brake controlling valve device, of the type having a-piston subject :to opposing fluid pressures and having alnormal brake release position and an emergency brake application position, said pistonl upon asudden reductionin the pressure of fluid actingon one side thereof being operative from its normal brake release position to-thefemergency .application position, in combination, a lubricant'carrying reservoir formed insaid pistonand normally charged wtih fluid under pressure, a passage formed in lsaid piston through'which fluid under pressure may Lflow and carry4 lubricant from-.said reservoir to the friction surfaces-of the pistoni, means supplied with lubricant from said reservoir and located in the pathof fl'owof fluidffromsaidy reservoir to said passage for 'supplying-,lubricant to fluid whichY may flow from thereservoi-r tothe passage, another passage formed in saidpiston leading from said reservoir to said flrstpassage through which fluid may flow to` equalize the pressure of fluid acting on opposite sides osaid,

means, and valve means operative as-an incident to the effecting of a middeny reduction Yinthe pressure 'of fluid actingon one sideof said'zpiston for preventing the flow of fluid from said reser voirby Wayio-f said other passage. i

s'iDNEY fnoWN 

